NexGen Energy Ltd. (TSX: NXE) (NYSE: NXE) (ASX: NXG) is pleased to announce its highest-grade assay results to date at the Company’s 100%-owned Patterson Corridor East with drill hole RK-25-256. Assays returned 5.5 meters at 21.4% U₃O₈ between 590.0 and 595.5 m depth, including 2.5 m at 46.1% U₃O₈ and 0.5 m at 74.8% U₃O₈ (Figures 1 and 2; Table 1) as well as a separate and adjacent intercept of 1.5 m at 5.28% U₃O₈.

Highlights:

• RK-25-256 returns 5.5 m at 21.4% U₃O₈, including 2.5 m at 46.1% U₃O₈ and including 0.5 m at 74.8% U₃O_8,

• Rook I developing a multi-generational portfolio of uranium projects in the southwest Athabasca Basin, Saskatchewan, Canada.

Significantly, this high-grade uranium intersection in RK-25-256 is 119 m down-dip of drill hole RK-25-232, and an additional 51 m down-dip of recently reported (see news release dated November 12, 2025) RK-25-254 (Figure 1 and 3). Overall, intense high-grade uranium mineralization is currently interpreted along a minimum of 215 m of dip extent from RK-25-254 to RK-24-222.

Leigh Curyer, Founder & Chief Executive Officer, commented: “RK-25-256 high-grade assay results, consisting of ultra-high grade 0.5 m 74.8% U₃O₈ takes PCE into a rare mineralized category on a world scale for uranium deposits. This type of basement-hosted mineralization is synonymous with Arrow, only 3.5 km to the west.

It is clear, the frequency of this ultra-high grade category of intercepts at Arrow and now PCE, is evidence of a very significant mineralizing event occurring at Rook I and in the surrounding region of the southwest Athabasca Basin in Saskatchewan.

NexGen, with Arrow as the inaugural deposit, is developing a uranium project portfolio which is focused on multi-generational nuclear fuel supply and providing economic, environmental, and social outcomes on a scale not previously witnessed in the industry. NexGen is a central component of delivering Canada’s and the world’s key critical mineral demand.”

Jason Craven, Vice President, Exploration, commented: “These exceptional grades significantly elevate our understanding of PCE and offer a glimpse at the growing basement-hosted uranium prospectivity in the southwest Athabasca Basin, where NexGen controls the most prospective portfolio of over 190,000 hectares across 140 km of the southwest Athabasca Basin.”

Figure 1: Interpreted PCE long section (as of August 28, 2025 release) with notable assays collected since discovery and new results outlined in red; view is a long section that looks perpendicular to the primary mineralized plane; total mineralized footprint in orange and the high-grade subdomains in red

To view an enhanced version of this graphic, please visit:
https://images.newsfilecorp.com/files/1745/276408_648e12a334cb1993_002full.jpg

Figure 2: Core photo with select assays from RK-25-256, grades are shown as % U₃O₈

To view an enhanced version of this graphic, please visit:
https://images.newsfilecorp.com/files/1745/276408_648e12a334cb1993_003full.jpg

Figure 3: Interpreted 3D model of PCE shown looking northwest (across strike) and northeast (along strike); previously reported in August 28 release, now with RK-25-256 intersection shown as purple outline for reference

To view an enhanced version of this graphic, please visit:
https://images.newsfilecorp.com/files/1745/276408_648e12a334cb1993_004full.jpg

Table 1: Assays received since November 12, 2025 news release

• All depths and intervals are meters downhole, true thicknesses are yet to be determined.
• Unconformity of ‘N/A’ denotes a lack of visible contact between Athabasca sandstone and basement rock.
• Maximum internal dilution 2.0 m downhole.
• Minimum thickness of 0.5 m downhole.
• Cutoff grade 0.01% U₃O₈.
• All depths and intervals are metres downhole, true thicknesses are yet to be determined. Resource modelling in conjunction with an updated mineral resource estimate is required before true thicknesses can be determined.
• * Denotes results that correlate to high-grade levels of radioactivity (>10,000 cps)

About NexGen

NexGen Energy is a Canadian company focused on delivering clean energy fuel for the future. The Company’s flagship Rook I Project is being optimally developed into the largest low-cost producing uranium mine globally, incorporating the most elite environmental and social governance standards. The Rook I Project is supported by an N.I. 43-101 compliant Feasibility Study, which outlines the elite environmental performance and industry-leading economics. NexGen is led by a team of experienced uranium and mining industry professionals with expertise across the entire mining life cycle, including exploration, financing, project engineering and construction, operations and closure. NexGen is leveraging its proven experience to deliver a Project that leads the entire mining industry socially, technically and environmentally. The Project and prospective portfolio in northern Saskatchewan will provide generational, long-term economic, environmental, and social benefits for Saskatchewan, Canada, and the world.

NexGen is listed on the Toronto Stock Exchange, the New York Stock Exchange under the ticker symbol “NXE,” and on the Australian Securities Exchange under the ticker symbol “NXG,” providing access to global investors to participate in NexGen’s mission of solving three major global challenges in decarbonization, energy security and access to power. The Company is headquartered in Vancouver, British Columbia, with its primary operations office in Saskatoon, Saskatchewan.